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3 years ago

The mean of 15 numbers is 12. An extra number is included and the mean increases to 13. What the extra number?

Mathematics

1 answer:

Studentka2010 [4]3 years ago

5 0

Answer: 28

Step-by-step explanation:

The mean of 15 numbers = 12

Then , the sum of the numbers = 12x15 = 180

Let the extra number included be $x$ , then

The new sum = $x + 180$

And the new total number will increase from 15 to 16

new mean = 13 , so we have :

$\frac{x+180}{16} = 13$

$x+ 180 = 16(13)$

$x + 180 = 208$

$x = 208 - 180$

$x = 28$

therefore , the extra number is 28

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A professor would like to test the hypothesis that the average number of minutes that a student needs to complete a statistics e

professor190 [17]

Answer:

$\chi^2 =\frac{15-1}{25} 16 =8.96$

The degrees of freedom are given by:

$df = n-1 = 15-1=14$

The p value for this case would be given by:

$p_v =P(\chi^2$

Since the p value is higher than the significance level we have enough evidence to FAIL to reject the null hypothesis and we can conclude that the true deviation is not ignificantly lower than 5 minutes

Step-by-step explanation:

Information given

$n=15$ represent the sample size

$\alpha=0.05$ represent the confidence level

$s^2 =16$ represent the sample variance

$\sigma^2_0 =25$ represent the value that we want to verify

System of hypothesis

We want to test if the true deviation for this case is lesss than 5minutes, so the system of hypothesis would be:

Null Hypothesis: $\sigma^2 \geq 25$

Alternative hypothesis: $\sigma^2$

The statistic is given by:

$\chi^2 =\frac{n-1}{\sigma^2_0} s^2$

And replacing we got:

$\chi^2 =\frac{15-1}{25} 16 =8.96$

The degrees of freedom are given by:

$df = n-1 = 15-1=14$

The p value for this case would be given by:

$p_v =P(\chi^2$

6 0

3 years ago

Hello There!!~ (^人^) I need help please... Sasha noticed that the graph of the sales of yearbooks represented a proportional rel

zzz [600]

Answer:

Sasha can look at the graph and check to see that when she plots the points on the graph, they end up as a straight line. She can also draw a table to test the values and see if when you divide y/x you get the same answer for all of them.

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

Give the value of x . A. 60 degrees B. 180 degrees C. 120 degrees D. 45 degrees

Harrizon [31]

Answer:

x=120°

Step-by-step explanation:

sum of all angles in a triangle is equal to 180

let the unknown angle be

$\alpha$

$60 + 60 + \alpha = 180 \\ \alpha = 180 - 60 - 60 \\ \alpha = 60 \\$

$\alpha + x = 180 \\ x = 180 - \alpha \\ x = 180 - 60 \\ x = 120$

5 0

2 years ago

grandymaker [24]

Answer:

The Answer is is option B.

6 0

2 years ago

Expanded form for 48,243. (

Dima020 [189]

(4*10,000)+(8*1,000)+(2*100)+(4*10)+(3*1)

40,000+8,000+200+40+3=48,243

That is one way. You can also do this using exponential form!

Hope that helps

4 0

3 years ago